An assessment of chemical contaminants, toxicity and benthic infauna in sediments from the St. Thomas East End Reserves (STEER)

This report contains a chemical and biological characterization of sediments from the St. Thomas East End Reserves (STEER) in St. Thomas, U.S. Virgin Islands (USVI). The STEER Management Plan (published in 2011) identified chemical contaminants and habitat loss as high or very high threats and called for a characterization of chemical contaminants as well as an assessment of their effects on natural resources. The baseline information contained in this report on chemical contaminants, toxicity and benthic infaunal community composition can be used to assess current conditions, as well as the efficacy of future restoration activities. In this phase of the project, 185 chemical contaminants, including a number of organic (e.g., hydrocarbons and pesticides) and inorganic (e.g., metals) compounds, were analyzed from 24 sites in the STEER. Sediments were also analyzed using a series of toxicity bioassays, including amphipod mortality, sea urchin fertilization impairment, and the cytochrome P450 Human Reporter Gene System (HRGS), along with a characterization of the benthic infaunal community. Higher levels of chemical contaminants were found in Mangrove Lagoon and Benner Bay in the western portion of the study area than in the eastern area. The concentrations of polychlorinated biphenyls (PCBs), DDT (dichlorodiphenyltrichloroethane), chlordane, zinc, copper, lead and mercury were above a NOAA sediment quality guideline at one or more sites, indicating impacts may be present in more sensitive species or life stages in the benthic environment. Copper at one site in Benner Bay, however, was above a NOAA guideline indicating that effects on benthic organisms were likely. The antifoulant boat hull ingredient tributyltin, or TBT, was found at the third highest concentration in the history of NOAA’s National Status and Trends (NS&T) Program, which monitors the Nation’s coastal and estuarine waters for chemical contaminants and bioeffects. Unfortunately, there do not appear to be any established sediment quality guidelines for TBT. Results of the bioassays indicated significant sediment toxicity in Mangrove Lagoon and Benner Bay using multiple tests. The benthic infaunal communities in Mangrove Lagoon and Benner Bay appeared severely diminished.

Scientific assessment of marine harmful algal blooms

Algae are the most abundant photosynthetic organisms in marine ecosystems and are essential components of marine food webs. Harmful algal bloom or “HAB” species are a small subset of algal species that negatively impact humans or the environment. HABs can pose health hazards for humans or animals through the production of toxins or bioactive compounds. They also can cause deterioration of water quality through the buildup of high biomass, which degrades aesthetic, ecological, and recreational values. Humans and animals can be exposed to marine algal toxins through their food, the water in which they swim, or sea spray. Symptoms from toxin exposure range from neurological impairment to gastrointestinal upset to respiratory irritation, in some cases resulting in severe illness and even death. HABs can also result in lost revenue for coastal economies dependent on seafood harvest or tourism, disruption of subsistence activities, loss of community identity tied to coastal resource use, and disruption of social and cultural practices. Although economic impact assessments to date have been limited in scope, it has been estimated that the economic effects of marine HABs in U.S. communities amount to at least $82 million per year including lost income for fisheries, lost recreational opportunities, decreased business in tourism industries, public health costs of illness, and expenses for monitoring and management. As reviewed in the report, Harmful Algal Research and Response: A Human Dimensions Strategy1, the sociocultural impacts of HABs may be significant, but remain mostly undocumented.

Characterization of TRPC2, an Essential Genetic Component of VNS Chemoreception, Provides Insights into the Evolution of Pheromonal Olfaction in Secondary-Adapted Marine Mammals

Pheromones are chemical cues released and sensed by individuals of the same species, which are of major importance in regulating reproductive and social behaviors of mammals. Generally, they are detected by the vomeronasal system (VNS). Here, we first investigated and compared an essential genetic component of vomeronasal chemoreception, that is, TRPC2 gene, of four marine mammals varying the degree of aquatic specialization and related terrestrial species in order to provide insights into the evolution of pheromonal olfaction in the mammalian transition from land to water. Our results based on sequence characterizations and evolutionary analyses, for the first time, show the evidence for the ancestral impairment of vomeronasal pheromone signal transduction pathway in fully aquatic cetaceans, supporting a reduced or absent dependence on olfaction as a result of the complete adaptation to the marine habitat, whereas the amphibious California sea lion was found to have a putatively functional TRPC2 gene, which is still under strong selective pressures, reflecting the reliance of terrestrial environment on chemical recognition among the semiadapted marine mammals. Interestingly, our study found that, unlike that of the California sea lion, TRPC2 genes of the harbor seal and the river otter, both of which are also semiaquatic, are pseudogenes. Our data suggest that other unknown selective pressures or sensory modalities might have promoted the independent absence of a functional VNS in these two species. In this respect, the evolution of pheromonal olfaction in marine mammals appears to be more complex and confusing than has been previously thought. Our study makes a useful contribution to the current understanding of the evolution of pheromone perception of mammals in response to selective pressures from an aquatic environment.

Effect of paradoxical sleep deprivation and stress on passive avoidance behavior

Previous studies have shown that several types of stress can induce memory impairment. However, the memory effects of paradoxical sleep deprivation (PSD), a stressor in itself, are unclear. We therefore compared passive avoidance behavior of rats undergoing PSD and PSD stress yoked-control (PSC) using the "reversed flowerpot method." When rats were kept isolated on a PSC platform for 24 It immediately after criterion training, retention trials showed impaired aversive memory storage. When delayed for 24 h after criterion training, PSC stress did not disrupt retention performance. In rats subjected to PSD, either immediately or 24 It after criterion training, there was no disruption of aversive memory consolidation. These results suggest that, during stress, paradoxical sleep plays a role in erasing aversive memory traces, in line with the theory that we "dream in order to forget." (C) 2003 Elsevier Inc. All rights reserved.

Gender effect on the right-left discrimination task in a sample of heroin-dependent patients

Rationale: Discriminating right from left is an everyday cognitive ability. Repeated exposure to certain drugs, such as heroin, can produce poor performance on many cognitive tasks. However, it is yet unclear whether drug abuse impairs the ability of right-left discrimination. Objectives: The aim of the present study is to examine whether the spatial ability measured by the right-left discrimination task can be affected by heroin abuse and whether such drug effect, if it exists, is gender related. Methods: A paper-and-pen test was used. The test consists of line drawings of a person with no arm, one arm, or both arms crossing the vertical body axis of the figure. The line drawings are viewed from the back, from the front, or randomly alternating between the back and front drawings. The subjects task is to mark which is the right or left hand in the figure as fast as possible. Results: A main finding in this study was that the ability to discriminate between left and right in visual space was impaired in heroin-dependent patients. Especially, heroin-dependent females performed poorer than control females in all conditions but heroin-dependent males only performed poorly in part of conditions. Conclusions: Recent heroin abuse impairs the ability of right-left discrimination and such impairment is gender related: heroin-dependent females demonstrated greater performance deficits than males.

Propofol facilitates the development of long-term depression (LTD) and impairs the maintenance of long-term potentiation (LTP) in the CA1 region of the hippocampus of anesthetized rats

Memory is sensitive to the short-acting anesthetic (2,6-diisopropylphenol) propofol, but the underlying mechanism is little known. Here, we have examined the effects of propofol on synaptic plasticity in the CA1 region of the hippocampus of anesthetized rats. We found that low dose of propofol (20 mg/kg, i.p.) did not affect the basal transmission, but enhanced prominently the development of long-term depression (LTD) and impaired the maintenance of long-term potentiation (LTP). The impairment of LTP maintenance and enhancement of LTD development may contribute to propofol-induced deficits in memory following propofol anesthesia. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Effects of Prenatal Exposure to a 50-Hz Magnetic Field on One-Trial Passive Avoidance Learning in 1-Day-Old Chicks

We investigated memory impairment in newly hatched chicks following in ovo exposure to a 50-Hz magnetic field (MF) of 2 mT (60 min/day) on embryonic days 12-18. Isolated and paired chicks were used to test the effect of stress during training, and memory retention was tested at 10, 30, and 120 min, following exposure to a bitter-tasting bead (100% methylanthranilate). Results showed that memory was intact at 10 min in both isolated and paired chicks with or without MF exposure. However, while isolated chicks had good memory retention levels at 30 and 120 min, those exposed to MF did not. The results suggest a potential disruption of memory formation following in ovo exposure to MF, with this effect only evident in the more stressed, isolated chicks. Bioelectromagnetics 31:150-155, 2010. (C) 2009 Wiley-Liss. Inc.

Lead exposure through gestation-only caused long-term learning/memory deficits in young adult offspring

Numerous observations in clinical and preclinical studies indicate that the developing brain is particular sensitive to lead (Pb)'s pernicious effects. However, the effect of gestation-only Pb exposure on cognitive functions at maturation has not been studied. We investigated the potential effects of three levels of Pb exposure (low, middle, and high Pb: 0.03%, 0.09%, and 0.27% of lead acetate-containing diets) at the gestational period on the spatial memory of young adult offspring by Morris water maze spatial learning and fixed location/visible platform tasks. Our results revealed that three levels of Pb exposure significantly impaired memory retrieval in male offspring, but only female offspring at low levels of Pb exposure showed impairment of memory retrieval. These impairments were not due to the gross disturbances in motor performance and in vision because these animals performed the fixed location/visible platform task as well as controls, indicating that the specific aspects of spatial learning/memory were impaired. These results suggest that exposure to Pb during the gestational period is sufficient to cause long-term learning/memory deficits in young adult offspring. (C) 2003 Elsevier Inc. All rights reserved.

Effects of unconditioned and conditioned aversive stimuli in an intense fear conditioning paradigm on synaptic plasticity in the hippocampal CA1 area in vivo

Repeated vivid recalls or flashbacks of traumatic memories and memory deficits are the cardinal features of post-traumatic stress disorder (PTSD). The underlying mechanisms are not fully understood yet. Here, we examined the effects of very strong fear conditioning (20 pairings of a light with a 1.5-mA, 0.5-s foot shock) and subsequent reexposure to the conditioning context (chamber A), a similar context (chamber B), and/or to the fear conditioned stimulus (CS) (a light) on synaptic plasticity in the hippocampal CA1 area in anesthetized Sprague-Dawley rats. The conditioning procedure resulted in very strong conditioned fear, as reflected by high levels of persistent freezing, to both the contexts and to the CS, 24 h after fear conditioning. The induction of long-term potentiation ON was blocked immediately after fear conditioning. It was still markedly impaired 24 h after fear conditioning; reexposure to the conditioning chamber A (CA) or to a similar chamber 13 (CB) did not affect the impairment. However, presentation of the CS in the CA exacerbated the impairment of LTP, whereas the CS presentation in a CB ameliorated the impairment so that LTP induction did not differ from that of control groups. The induction of long-term depression (LTD) was facilitated immediately, but not 24 h, after fear conditioning. Only reexposure to the CS in the CA, but not reexposure to either chamber A or B alone, or the CS in chamber B, 24 h after conditioning, reinstated the facilitation of LTD induction. These data demonstrate that unconditioned and conditioned aversive stimuli in an intense fear conditioning paradigm can have profound effects on hippocampal synaptic plasticity, which may aid to understand the mechanisms underlying impairments of hippocampus-dependent memory by stress or in PTSD. (c) 2005 Wiley-Liss, Inc.

Chronic Morphine Treatment Impaired Hippocampal Long-Term Potentiation and Spatial Memory via Accumulation of Extracellular Adenosine Acting on Adenosine A(1) Receptors

Chronic exposure to opiates impairs hippocampal long-term potentiation (LTP) and spatial memory, but the underlying mechanisms remain to be elucidated. Given the well known effects of adenosine, an important neuromodulator, on hippocampal neuronal excitability and synaptic plasticity, we investigated the potential effect of changes in adenosine concentrations on chronic morphine treatment-induced impairment of hippocampal CA1 LTP and spatial memory. We found that chronic treatment in mice with either increasing doses (20-100 mg/kg) of morphine for 7 d or equal daily dose (20 mg/kg) of morphine for 12 d led to a significant increase of hippocampal extracellular adenosine concentrations. Importantly, we found that accumulated adenosine contributed to the inhibition of the hippocampal CA1 LTP and impairment of spatial memory retrieval measured in the Morris water maze. Adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine significantly reversed chronic morphine-induced impairment of hippocampal CA1 LTP and spatial memory. Likewise, adenosine deaminase, which converts adenosine into the inactive metabolite inosine, restored impaired hippocampal CA1 LTP. We further found that adenosine accumulation was attributable to the alteration of adenosine uptake but not adenosine metabolisms. Bidirectional nucleoside transporters (ENT2) appeared to play a key role in the reduction of adenosine uptake. Changes in PKC-alpha/beta activity were correlated with the attenuation of the ENT2 function in the short-term (2 h) but not in the long-term (7 d) period after the termination of morphine treatment. This study reveals a potential mechanism by which chronic exposure to morphine leads to impairment of both hippocampal LTP and spatial memory.

Dose-dependent effects of the dopamine D1 receptor agonists A77636 or SKF81297 on spatial working memory in aged monkeys

With advancing age, monkeys develop deficits in spatial working memory resembling those induced by lesions of the prefrontal cortex (PFC). Aged monkeys also exhibit marked loss of dopamine from the PFC, a transmitter known to be important for proper PFC cognitive function. Previous results suggest that D1 agonist treatment can improve spatial working memory abilities in aged monkeys. However, this research was limited by the use of drugs with either partial agonist actions or significant D2 receptor actions. In our study, the selective dopamine D1 receptor full agonists A77636 and SKF81297 were examined in aged monkeys for effects on the working memory functions of the PFC. Both compounds produced a significant, dose-related effect on delayed response performance without evidence of side effects: low doses improved performance although higher doses impaired or had no effect on performance. Both the improvement and impairment in performance were reversed by pretreatment with the D1 receptor antagonist, SCH23390. These findings are consistent with previous results demonstrating that there is a narrow range of D1 receptor stimulation for optimal PFC cognitive function, and suggest that very low doses of D1 receptor agonists may have cognitive-enhancing actions in the elderly.

User responses to the learning demands of consumer products

Designers are typically male, under 35 years old and unimpaired. Users can be of any age and currently over 15% will have some form of impairment. As a result a vast array of consumer products suit youthful males and in many cases exclude other demographics (e.g. Keates and Clarkson, 2004). In studying the way a range of users learn how to use new products, key cognitive difficulties are revealed and linked back to the areas of the product causing the problems. The trials were structured so each user had to complete a specific set of tasks and were consistent across the user spectrum. The tasks set aimed to represent both everyday usage and less familiar functions. Whilst the knowledge gained could provide designers with valuable guidelines for the specific products examined, a more general abstraction provides knowledge of the pitfalls to avoid in the design of other product families.

Designing inclusive interfaces through user modeling and simulation

Elderly and disabled people can be hugely benefited through the advancement of modern electronic devices, as those can help them to engage more fully with the world. However, existing design practices often isolate elderly or disabled users by considering them as users with special needs. This article presents a simulator that can reflect problems faced by elderly and disabled users while they use computer, television, and similar electronic devices. The simulator embodies both the internal state of an application and the perceptual, cognitive, and motor processes of its user. It can help interface designers to understand, visualize, and measure the effect of impairment on interaction with an interface. Initially a brief survey of different user modeling techniques is presented, and then the existing models are classified into different categories. In the context of existing modeling approaches the work on user modeling is presented for people with a wide range of abilities. A few applications of the simulator, which shows the predictions are accurate enough to make design choices and point out the implication and limitations of the work, are also discussed. © 2012 Copyright Taylor and Francis Group, LLC.

A crowding model of visual clutter.

Visual information is difficult to search and interpret when the density of the displayed information is high or the layout is chaotic. Visual information that exhibits such properties is generally referred to as being "cluttered." Clutter should be avoided in information visualizations and interface design in general because it can severely degrade task performance. Although previous studies have identified computable correlates of clutter (such as local feature variance and edge density), understanding of why humans perceive some scenes as being more cluttered than others remains limited. Here, we explore an account of clutter that is inspired by findings from visual perception studies. Specifically, we test the hypothesis that the so-called "crowding" phenomenon is an important constituent of clutter. We constructed an algorithm to predict visual clutter in arbitrary images by estimating the perceptual impairment due to crowding. After verifying that this model can reproduce crowding data we tested whether it can also predict clutter. We found that its predictions correlate well with both subjective clutter assessments and search performance in cluttered scenes. These results suggest that crowding and clutter may indeed be closely related concepts and suggest avenues for further research.

Functional magnetic resonance imaging of impaired sensory prediction in schizophrenia.

IMPORTANCE: Forward models predict the sensory consequences of planned actions and permit discrimination of self- and non-self-elicited sensation; their impairment in schizophrenia is implied by an abnormality in behavioral force-matching and the flawed agency judgments characteristic of positive symptoms, including auditory hallucinations and delusions of control. OBJECTIVE: To assess attenuation of sensory processing by self-action in individuals with schizophrenia and its relation to current symptom severity. DESIGN, SETTING, AND PARTICIPANTS: Functional magnetic resonance imaging data were acquired while medicated individuals with schizophrenia (n = 19) and matched controls (n = 19) performed a factorially designed sensorimotor task in which the occurrence and relative timing of action and sensation were manipulated. The study took place at the neuroimaging research unit at the Institute of Cognitive Neuroscience, University College London, and the Maudsley Hospital. RESULTS: In controls, a region of secondary somatosensory cortex exhibited attenuated activation when sensation and action were synchronous compared with when the former occurred after an unexpected delay or alone. By contrast, reduced attenuation was observed in the schizophrenia group, suggesting that these individuals were unable to predict the sensory consequences of their own actions. Furthermore, failure to attenuate secondary somatosensory cortex processing was predicted by current hallucinatory severity. CONCLUSIONS AND RELEVANCE: Although comparably reduced attenuation has been reported in the verbal domain, this work implies that a more general physiologic deficit underlies positive symptoms of schizophrenia.